Additive functionals and excursions of Kuznetsov processes
LetBbe a continuous additive functional for a standard process(Xt)t∈ℝ+and let(Yt)t∈ℝbe a stationary Kuznetsov process with the same semigroup of transition. In this paper, we give the excursion laws of(Xt)t∈ℝ+conditioned on the strict past and future without duality hypothesis. We study excursions of a general regenerative system and of a regenerative system consisting of the closure of the set of times the regular points ofBare visited. In both cases, those conditioned excursion laws depend only on two pointsXg−andXd, where]g,d[is an excursion interval of the regenerative setM. We use the(FDt)-predictable exit system to bring together the isolated points ofMand its perfect part and replace the classical optional exit system. This has been a subject in literature before (e.g., Kaspi (1988)) under the classical duality hypothesis. We define an “additive functional” for(Yt)t∈ℝwithB, we generalize the laws cited before to(Yt)t∈ℝ, and we express laws of pairs of excursions.